Estimating dead organic matter carbon dynamics of an intact mixed dipterocarp forest in Brunei with a forest carbon model

Abstract:

Intact tropical forests contain substantial amount of carbon (C) and play an important role in global carbon cycles. Field measurement is needed to quantify dead organic matter (DOM) C dynamics in tropical forests while it requires much labor and cost. In contrast, forest carbon models can simulate C dynamics, overcoming the limitation of field measurement. In this study, we simulated the DOM C dynamics of an intact mixed dipterocarp forest at Kuala Belalong in Brunei, by using a forest carbon model. In order to estimate the annual changes in the C stocks of litter layer, dead root, coarse woody debris (CWD), and soils, a forest carbon model, KFSC model, was parameterized to the study site. In order to initialize the KFSC model, the C stocks in biomass, litter layer, CWD, and soils were measured in twenty seven 20 m x 20 m plots in 2014. The measured C stocks (Mg C ha^-1) in litter layer, dead root, CWD, and soils were 3.2 ± 0.5, 4.0 ± 1.9, 32.5 ± 38.9, and 75.2 ± 9.2, respectively. The simulation results showed that the annual changes in the C stocks (Mg C ha^‑1 yr^-1) of litter layer, dead root, CWD, and soils were 2.7 ± 2.0, 1.4 ± 1.8, -1.5 ± 7.7, and 0.5 ± 1.8, respectively. The total DOM C stocks tended to increase at the rate of 3.3 ± 9.6 Mg C ha^‑1 yr^-1, but it exhibited the high variation. This might be attributed to the high variation of the annual changes in the CWD C stocks. Our results exhibited the applicability of forest carbon models to quantify DOM C dynamics in intact tropical rain forests.